The disclosure of Japanese Patent Application No. 2001-71209 filed on Mar. 13, 2001 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of Invention
The invention relates to a filter formed by spinning fibers that are in a semi-molten state onto a mold, as well as a method for manufacturing the filter.
2. Description of Related Art
As shown in FIGS. 4A and 4B, in order to improve forming efficiency of a filter, semi-molten fibers F spun from a spinning nozzle 54 are deposited onto a forming surface 52f of a forming mold 52 to form a filter 50 having a shape substantially the same as that of the forming surface 52f (Japanese Patent Application Laid-Open Publication No. 8-38834). After being formed, the filter 50 is then removed from the forming mold 52 and completed with a finishing process.
With this method, however, because the filter 50 must be removed from the forming mold 52, careful attention must be paid so as not to damage the filter 50 during removal. That is, although this method simplifies forming the filter 50, removing the filter from the forming mold 52 is troublesome.
The invention thus simplifies the manufacture of a filter by omitting the process of removing the filter from the mold. According to a first exemplary aspect of the invention, a filter formed by fibers spun in a semi-molten state over a mold is such that the mold is provided as a filter structural member.
According to this exemplary aspect, because the mold for forming the filter becomes a structural member of the filter, there is no need to remove the filter from the mold. Obviating the need for the operation of removing the filter from the mold in this way thus simplifies the manufacture of the filter.
Also according to this exemplary aspect, the mold can include both a filter portion forming surface for forming a filter portion for filtering a fluid and a frame which surrounds this filter portion forming surface. The frame and the like in this case improves the strength of the filter, making the filter less prone to deformation by negative pressure and the like from the fluid passing therethrough.
Fibers protruding outside of the frame can also be folded inward toward the inside of the frame and then fixed thereto. This obviates the need to cut off protruding fibers and keeps the fibers from being wasted.
Moreover, a flange can be formed on the outer periphery of the frame. Doing this enables fibers to be deposited on the flange, which in turn enables a seal portion to be formed easily when the filter is attached to a housing.
The mold and fibers may also be formed of the same material. If formed of the same material, the mold and the fibers in a semi-molten state fuse together, such that adhesion between the mold and fibers is improved. The filter portion forming surface of the mold may also be formed with a mesh.
According to a second exemplary aspect of the invention, a method for manufacturing a filter by spinning fibers in a semi-molten state on a mold, is such that the mold is made a filter structural member after the filter is manufactured. This exemplary aspect of the invention enables the filter according to the first exemplary aspect of the invention to be manufactured.